Remove one and only one occurrence of each specified value from an array

remove_one.rb

class Array
  def remove_one values
    values = values.dup
    new_array = []
    each do |value|
      if values.include? value
        values.delete value
      else
        new_array << value
      end
    end
    
    new_array
  end
end

remove_one_spec.rb

describe 'Array#remove_one' do
  it 'removes one of each value from the array' do
    [1, 1, 2, 3].remove_one([1, 2]).should == [1, 3]
  end
end